


One Last Experiment

by Sera_The_Dragon



Series: Buttercup Relapse [1]
Category: Deltarune (Video Game), Undertale (Video Game)
Genre: Amalgamation (Undertale), Angst, Angst and Hurt/Comfort, Angst with a Happy Ending, Body Horror, Depression, Emotional Hurt/Comfort, Gen, Graphic Depictions of Illness, Hospitalization, Hurt/Comfort, I Made Myself Cry, Mental Health Issues, Night Terrors, Nightmares, Not Really Character Death, Poisoning, Sans gets mentioned a grand total of one time, Scary, Sibling Bonding, Suicide Attempt, This Is Why We Can't Have Nice Things, Why Did I Write This?, seriously there is a lot of amalgamation going on here
Language: English
Status: Completed
Published: 2021-02-27
Updated: 2021-02-27
Packaged: 2021-03-18 03:07:18
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 3,471
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29727390
Author URL: https://archiveofourown.org/users/Sera_The_Dragon/pseuds/Sera_The_Dragon
Summary: Good, bad, what did it matter? Frisk knew from the start that she was a demon in progress. She was lucky that her mom even bothered to keep her around.But a surreal nightmare can change all of that.Inspired by Truelab.exe
Series: Buttercup Relapse [1]
Series URL: https://archiveofourown.org/series/2184822
Kudos: 9
Collections: Dreemurr's Tears and Darkner's Blood: An Undertale/Deltarune AU





	One Last Experiment

I’m not sure why I got the idea. All I know is that once it had shown up, it wouldn’t go away until I did something about it. This whisper isn’t like the others; it won’t go away with a few little scrapes. I know because I already tried.

Lying on the grass, I grab a fistful of buttercups from Asgore’s garden. The flowers irritate my hand, but it doesn’t deter me. I force myself to eat them.

Nothing happens. It wasn’t enough. I start grabbing more, shoveling the gross, bitter plants into my mouth until my stomach feels like it’s going to burst.

I think I must have fallen asleep for a little while because when I open my eyes again my hands are all puffy and swollen and they hurt really bad. Everything feels cold. I touch my face, and it hurts, and I realize my mouth is puffy too. My throat and stomach burn, and I start throwing up. I can already see swirls of red in the filthy liquid. Tears start falling from my eyes. I grab another handful of buttercups and make myself chew them up and swallow them.

_“Frisk, what are you doing?!”_

I shudder at the sound of Chara’s voice. She sounds really scared. She doesn’t understand. I have to do this. I pull more buttercups out of the garden and eat them.

_“Frisk, you need to stop! Those flowers will kill you!”_

“I know,” I say weakly in between hoarse gasps. My tongue feels thick behind my teeth. “I know.”

Chara tries to pull me away from the flowers, but she’s only a ghost; she can’t do much. From somewhere else in the garden, I hear Flowey groaning, clearly irritated by all the commotion. “Could you keep it down out here, Frisk? I’m trying to—” He stops talking the moment he sees me.

 _“We need to help her!”_ Chara shouts.

“I’ll get the King and Queen,” Flowey says. “You stay here with her.”

Chara strokes my back. _“Shh,”_ she whispers, _“it’s okay.”_

“No, it’s not,” I moan in response. “It was never okay. I caused everyone so much grief…”

Everyone had to go through so much because of me. Because of me, Undyne died, and everyone else came really close. And that’s not even bringing up the route I was stupid enough to take in the past, the one I tried so hard to forget… Even though everything’s been fixed, it doesn’t change the fact that I messed everything up. Undyne still hasn’t talked to me ever since that weird adventure ended.

_“Don’t worry, we’re going to fix this.”_

“No, don’t.” I cough, and a mixture of filthy yellow liquid and blood stains the grass. “It’s my punishment. Let it be.”

 _“Punishment for what?”_ Chara shouts. _“You haven’t done anything wrong!”_

Before I can respond, the door to the garden opens, and I hear Mom and Dad’s panicked voices. They run to my sides, holding my hands and lifting me, and telling me I’ll be okay, I’ll be okay. Everything after that is a blur. I don’t pay attention; I'm just trying to breathe, weakly gasping for air through a throat half-sealed by blisters. I’m not sure why I’m bothering with it; after all, I’m trying to die.

It’s the only way I won’t cause any more trouble.

Eventually, Alphys arrives. She says something, and then Flowey says something, and Kris says something too, and it’s all just a big mess. I can barely understand what’s happening.

Soon we arrive at the hospital, and Alphys lays me on top of a clean bed and takes a small bottle of water off a nearby shelf. She holds it out to me, saying something that I can barely hear. “No,” I moan, trying and failing to push her away. “No water. Let it be.”

Alphys keeps talking. Something about fixing me… I don’t want that. I want everyone else to be happy. The only way that can happen is if I’m gone.

“Don’t fix it. Let it be.” Alphys looks scared, and she starts shouting. “Let it be!” I cry. My voice dies, and I start coughing; something—I’m not sure what—spills from my lips. “Just… just let it be! Please!”

Alphys backs away with a somber expression in her eyes. She says something to Mom and Dad and Kris. They all leave the room. Kris turns back to face me and says something to me, but I’m not sure what. Now, it’s just me, Chara, and Flowey. Flowey asks if I’m going to be okay—at least, I think he does. It’s hard to tell. Chara lies and says yes with a nod.

The pain inside me becomes a fire. I moan and roll over, curling up into a ball and wrapping my arms around my aching belly. I feel the puffy spots around my lips and inside my mouth leaking out something that tastes like blood mixed with something nasty. I try to spit out the mixture, but my stomach twists itself up and I find myself throwing up all over the floor. The leaky spots in my mouth burn.

After what feels like forever, Alphys comes back in. I’m barely clinging to consciousness, but I do my best trying to listen to whatever Alphys has to say. She looks away, wringing her hands nervously as she talks. I turn back over to lay flat on my back. “Let me sleep,” I say, desperate for it all to just end. “Please.”

Alphys tries to give me some medicine, but I don’t wanna feel better. I deserve the pain I’m being put through. Eventually, though, my burning, bleeding throat forces me to give in and swallows the medicine. To fill the silence, I start talking about things. I don’t even pay attention to what I say; the words just come out. Alphys smiles sadly as I keep talking, and soon she tells me something about the medicine and starts gently sliding a small, lubricated tube down my throat.

She says something again; I think she’s asking me a question. I shake my head, and Alphys sighs and turns on a small machine that starts whirring quietly. She leaves the room, and the three of us are left alone together. I close my eyes and lay my head back. I let my breathing slow down until the darkness finally swallows me.

* * *

_Opening my eyes, I find myself outside Alphys’s old lab back in the Underground. It’s darker than it should be. Nervous, I enter the building. I can barely see anything; none of the electrical devices are working._

_“Chara?” I call out. “What’s going on?”_

_There’s no response._

_“Chara?”_

_Still nothing. I can’t even feel her presence. My mind is empty except for the harsh, cold whispers of the bad thoughts. I force myself to focus on the surroundings, but I keep growing more worried as I wonder what happened to Chara. She’s never been this quiet, and it scares me that she isn’t here since it leaves me all alone with the bad thoughts, the urges to do terrible things, things I know I shouldn’t do; oh my god, I’m scared. What’s happening?_

_On Alphys’s desk, a tiny red flower sits in a small pot. I pick it up; it might be useful later. Besides, it reminds me of my missing friend._

_The only thing that still works is the elevator leading to the underground part of the lab. I figure I might as well try it. After all, the other door leading out is missing._

_“You shouldn’t be here, Frisk,” I mutter to myself._

_I walk down the dark hallways until I encounter a suspicious red stain on the floor. Trying not to think about it, I keep going, but there are even more bloodstains the further I go. None of the digital entries say anything._

_Beside one of the entry panels is a large pool of blood coming from—_

_Oh, god no._

_“Alphys?” Even though I know she won’t respond, I grab her shoulders and wait for a response. Of course, the bloody corpse says nothing. Her head’s been sliced in half; her bottom jaw is still attached to her body, but everything above it is lying beside her, and her eyes have been clawed out by something. Slowly, her body and head are crumbling into white dust, turning the blood on the floor into a dark pink sludge._

_There’s a note beside the corpse. It takes a while, but eventually, I figure out that it says “I’m so sorry… I didn’t mean to turn them into these things…”_

_What could she mean? Against my better judgment, I head farther forward. Somebody else might be here, and if they are, I’m going to help them._

_Something darts across my limited field of view too fast for me to see. The lack of light shrouded the thing in the darkness. I couldn’t be entirely sure, but it looked sort of like…_

_“Sans?”_

_No response. He must have left… if it was even him to begin with. Trying to ignore the thought, I keep moving. My hands are clammy and my breathing hurts._

_Leading up to the exit elevator, a trail of blood decorates the tile floors. The elevator itself is locked. There goes my only hope of escaping. Next to the elevator, I find another red flower._

_“Chara, I miss you.”_

_With two flowers in my hand, I walk down the hallway to the left. It feels longer somehow. A pinging noise from one of the entry panels scares me half to death before I realize what it is. I go up to read it. The entry has been replaced by what looks like a distress signal reading… something. The letters are really tiny and it takes an even longer time to figure out than Alphys’s scribbles._

_It says “My face… is melting..? Please… end the pain… anyone…”_

_Somebody’s in a lot of pain. I have to help them, scary lab or no scary lab. I continue forward._

_The lab tables are stained with blood. The sinks don’t work. There’s a doorway leading into a pitch dark room up ahead… I take a moment to steel my nerves, and I go inside._

_The room is really small; I walk an entire circle around the room in a few seconds. The door leading out is gone. I start wandering the room again, scared of all the bad things that might happen._

_Something darts away from me really fast. I couldn’t even tell who—or what—it might have been. It left behind a trail of sticky white liquid coated in salt-colored fur. I don’t touch it, but I follow the trail to try and find whatever is trapped in here with me. I almost find it again, but it flees the moment I get close enough to see it again. I follow the trail to the middle of the room, and—_

_A horrible wail echoes through the room, and I jump at the noise, immediately losing my balance afterward. The thing in the middle of the room turns around. Its chest glows with white light, and the outfit it’s wearing looks familiar…_

_No. This isn’t right. This doesn’t make any sense._

_Standing before me is Toriel, but she’s all messed up; there are gaps in her skin going all the way through her body, and she’s missing her left arm. Her fangs have melted into her lips, dividing her mouth into three segments. Her eyes have been gouged out, so there are only gaping holes left where they should be. Her clothes have melted into her body, and the symbol on her chest has lost its wings._

_“Please…” The twisted creature that was once my mom howls in pain as she stands before me, her legs stuck together. “Please kill me…”_

_I can’t act; fear has gripped my heart and frozen me in place. I put my arms up defensively, in case she decides to attack, but nothing happens. The two of us stand there, unmoving, neither one of us willing to make the first move._

_“I… need… death…” Toriel moans as more of her body twists and melts into a horrifying imitation of who she used to be. Her head twitches erratically. “End… it… It hurts…”_

_Scared, I slowly approach my mom and hold out one of the red flowers I found earlier. Maybe if I can calm her down with a good memory, she’ll be okay, and maybe then she’ll stop saying these things._

_“I-I can help you, Mom,” I say, unsure of how true the statement is. “Please, just stop saying these things.”_

_Mom starts inching closer to me, her not-eyes seeming wild and dangerous. “I… I can’t…”_

_“Mom, I—” She cuts me off with a vicious howl and lunges towards me, burying her massive, half-melted claws in my back as she holds me in a death grip. I cry out as the monster bites my shoulder, her body melting into a thick, rubbery liquid on top of mine, sobbing tears made of her own flesh. The pain becomes too much to bear, and…_

_Everything goes dark._

* * *

_I’m stuck to the floor._

_Exhausted from the rush of fear, I sluggishly push myself off of the bloodstained tiles of the lab. The harsh memories of Alphys’s corpse slowly crumbling to dust and Mom’s horrific fate worse than death flash through my mind. I start crying all over again, but my tears feel… weird._

_Even though she isn’t here, I can still hear Chara’s voice, gently telling me to calm down and find a way to fix whatever is going on. I take a deep breath, still sniffling a bit, and wipe my tears away with my sleeve. It comes away wet and sticky, and my face starts to hurt, almost like it’s being stretched apart. I can’t understand why. Curious, I open my eyes and see a thick, rubbery substance the same color as my skin covering the fabric. Strings of the liquid are attached to my face._

_Nervous, I raise my hand and press it against my cheek, and all I feel is that same syrupy liquid. My hand comes away soaked in the substance; it melts into my arm almost effortlessly, deforming it._

_Am I… melting? No, that can’t be possible. Humans can’t melt. Monsters, sure, if they’re hyperdetermined, but not humans. Not humans…_

_There’s a mirror above one of the sinks. I shouldn’t, but I have to know. I trudge towards the mirror; my legs feel heavy like they’re sticking to the floor, and the stretching pain returns, only worse. I grab the rim of the sink, and my hands spread across the polished surface the same way molasses would. I hope to see my normal self in the mirror, but instead, I see—_

_An amalgamate. A terrifying, eyeless amalgamate in progress. The spots on my face where I dried my tears and touched my cheek are missing their skin, exposing the still-solid bone beneath it. My eyes are gone, replaced with gaping holes that look like a sad pair of closed eyes. The flowers I collected earlier have melted into my body, growing out of my neck and arm; I feel them forming new roots that dig into my syrupy flesh. It hurts in a way I can’t even describe. The red light of my SOUL flickers with fear as my skin slowly drips downward and the stretching pain worsens all over my body._

_I fight the urge to cover my not-eyes. If I do, they’ll probably end up attached to my hands, and it’ll hurt. All the same, I can’t keep looking at my twisted self. I scream, but all that comes out is a weird gurgling noise as my insides start to liquefy._

_Focus, says the imaginary Chara in my mind. There are people here who you need to help. See if you can find anyone else._

_Still scared but knowing that my thoughts are right, I turn away from my horrifying reflection. As fast as my doughy legs can carry me, I head for the hallway to the right of the elevator. The door there is open, and beside it is a red flower. I try to pick it up but my hand melts around it and sticks to itself, trapping another flower in my arm. I feel the roots begin to burrow through me. Ignoring the burrowing pain and the stretching pain and the sticking pain as much as I can, I trudge through the entrance, bracing myself for whatever new horror awaits._

_Inside, all I see is Flowey, standing in the center of a pool of blood. His center has turned black, and his eyes are wide. Trembling weakly, he keeps muttering things like “Stay away” and “Please don’t hurt me” and things like that._

_Not wanting to scare him any more, I walk around him._

_Something—Asgore, my dad, but all melty and messed up—lunges at me, and he swings his trident faster than I can react, and it slices my belly open, spilling my liquid insides all over the floor. It hurts like nothing I’ve ever felt before, and I can’t even scream. I just gurgle pathetically as I stand here, dying but also not dying. Dad lifts his trident to strike again, but it melts into his arms and he howls, slithering away as fast as he can move, leaving behind a slimy trail of flesh and fur._

_I turn around and leave the room, my guts still flowing out of my stomach until the two stick together and seal the wound Dad made._

_I decide to try to leave the way I came. As I pass by Alphys’s corpse, I realize her head has completely crumbled to dust, and all that remains is her body. I move past it—moving is slowly becoming more painful and more difficult as my body struggles to maintain its shape while it melts._

_Finally, I reach the elevator door._

_It’s locked._

_Defeated, I head back towards the exit elevator’s room. Alphys’s body is nothing but a pile of dark pink sand. I try to push the thought out of my mind but it keeps coming back. The hallway has become infinitely long; no matter how far I go, it’s never enough to reach the way out. Something starts fading into view, but I can’t tell what. All I can feel is the pain, the squishy, stretchy, melty, flowery pain. I try to keep walking toward the way out of this nightmare, forcing my melty playdough legs to go forward, sobbing flesh tears and reaching for... something. Anything._

_I fall to my knees, then to my hands, and I collapse to the ground. I reach out with an arm that barely looks like an arm, gurgling in pain._

_Something starts charging towards me with an open maw._

_“Noooo!”_

_With a single bite, everything goes dark. The last thing I hear before it all stops is one of my thoughts..._

Why didn’t you quit?

* * *

Everything hurts.

It’s not the same pain as before, though. I don’t feel the flower’s roots or the stretchy pain of melting. It’s more of a soreness, except for a few spots around my mouth, throat, and belly which hurt for real.

_“Frisk?!”_

I welcome the sound of Chara’s voice, even though it sounds so panicked.

_“Frisk, say something!”_

I open my puffy eyes, and I see her for the first time in what feels like forever.

“Chara…” My voice is hoarse and raspy, and I struggle to get my words past my sore throat, but I don’t care. She’s here. She’s really here. “Chara! I missed you!”

I swear I see tears in her eyes—real tears, and not the weird darkness that comes out of her eyes sometimes. _“I missed you too, Frisk!”_

I guess Chara was also trapped in a weird dream. I don’t care. I’m just happy to see her. I sit up and hold my arms out and she hugs me awkwardly and everything is perfect again.

She missed me. I missed her. I can’t leave Chara behind; if I die, who will be there for her?

“I’m sorry,” I sob, “I don’t know why I did this!”

 _“It’s okay.”_ Chara strokes my back again, quietly and gently shushing me as I cry into her spiritual shoulder. _“I’m sorry too. I think I finally understand you for real.”_

Taking broken, hiccuping breaths, I smile a bit. “I think I do too.”

For a moment, the pain is all gone. All that’s there is me and Chara, holding each other in our arms. I wish it could be like this forever.

If nothing else, I’ll stay strong for her. My partner… and my best friend.


End file.
